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JONATHAN
JONATHAN, JAGUAR/LAND ROVER SHOP FOREMAN
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My 1999 suburban (5.7) is having starting problems. Battery ...

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My 1999 suburban (5.7) is having starting problems. Battery and starter are fine. It tends to stumble when starting up and sometimes theres black smoke & a fuel smell. Fuel pressure is around 52 psi before starting and when it is running (fuel filter is new). I understand fuel pressure should be around 60~65 psi. What can I check or do to corect this problem?
Submitted: 8 years ago.
Category: Chevy
Expert:  MechanicMan replied 8 years ago.

Two things you can do really quick.


First check to see if any fuel is in the vacuum hose going to fuel regulator. Also check fuel pressure with the return line closed off.


Let me know what happens

Customer: replied 8 years ago.
Reply to MechanicMan's Post: I don't see the normal vacuum operated fuel regulator. Both supply and return lines are hard piped into the center of the intake manifold. There is only the test port on the supply line before it goes into the manifold. There's a small tab the holds the fuel lines onto the manifold. There is no familiar fuel rail with injectors on this thing.
Expert:  JONATHAN replied 8 years ago.
FUEL PRESSURE IS LOW...I HAVE A 99 TAHOE...THE FUEL PRESSURE REGULATOR AND FUEL INJECTORS ARE UNDERNEATH THE UPPER INTAKE PLENUM...THE REGULATORS ARE KNOW TO LEAK......I USUALLY GRAB A FLASH LIGHT AND TAKE A LOOK DOWN THE THROTTLE BODY AND POP OPEN THE INTAKE VACUUM PORT FOR THE BRAKE BOOSTER(IT JUST TWISTS OUT) AND LOOK FOR CLEAN ALUMINUM AND FUEL PUDDLES....IF THE GAUGE DOESN'T HOLD PRESSURE YOU HAVE A LEAK SOMEWHERE...I'VE ALSO SEEN THE INJECTOR BODIES AND INJECTOR'S PLASTIC NOZZLE LINES LEAK...YOU SHOULD HAVE AT LEAST 56-58 PSI AT THE TEST PORT WITH THIS THING RUNNING...IF AFTER REPAIRING FUEL LEAKS ITS STILL AT 52 I'D LOOK AT REPLACING THE PUMP....THE OTHER THING THAT I WOULD LOOK AT DOING WHICH I HAVE DONE TO MY PERSONAL TRUCK IS REPLACING THE ORIGINAL POPPET VALVE INJECTORS WITH GENERAL MOTORS REDESIGNED MUTLI POINT INJECTION SYSTEM WHICH HAS MINI INJECTORS THAT REPLACE THE POPPET VALVES ...THEY DON'T STICK CLOSED AND ACTUALLY GIVE THE TRUCK BACK ITS ORIGINAL POWER AND SMOOTH IDLE...ANY MORE INFO LET ME KNOW
Customer: replied 8 years ago.
Reply to JONATHAN's Post: Thanks Jonathan. I will give your advice a try. I plan on looking at the regulator and injectors tomorrow afternoon. Will I be able to ask you anything more about this once I accept your answer?
Expert:  JONATHAN replied 8 years ago.
lets keep the dialogue open and see where it goes....i want to see your car get truck...i love my tahoe and hope you feel the same way about your suburban
Customer: replied 8 years ago.
Reply to JONATHAN's Post: Hi Jonathan,
I was able to get down to the regulator and poppet valves. The intake manifold looks fairly clean compared to the rest of the manifold by the number 5 & 7 cylinders. I can't tell really if anything is leaking. There was some puddle of fuel at the bottom of the manifold but I don't if it happened when the fuel lines where removed. So it looks like I should just replace the whole setup (regulator, lines and poppets) and upgrade to the multi point injectors like you said just to be safe. So how can I tell when I'm at the parts store if I'm getting these newer injectors? Or do you think that will be pretty much the only style you can buy now? My parts store is a large AC Delco distributer.
Expert:  JONATHAN replied 8 years ago.
FUEL PRESSURE REGULATOR IS LEAKING.....THATS WHY ITS CLEAN AROUND 5 AND 7 CYLINDERS

http://cgi.ebay.com/ebaymotors/1996-2002-GM-Chevy-Vortec-Fuel-Injectors-4-3-CSFI-CPI_W0QQcmdZViewItemQQcategoryZ33554QQihZ020QQitemZ300013242213QQrdZ1QQsspagenameZWDVW

THIS IS THE UPDATED MFI UNIT FOR A 6 CYLINDER...YOURS WILL HAVE 8 LITTLE INJECTORS ON THE ENDS....
Expert:  JONATHAN replied 8 years ago.
EVERYTHING COMES TOGETHER....REGULATOR IS ATTACHED ...SEALS ARE IN THE METERING UNIT FOR THE FUEL PIPE...HOPE THIS HELPS....CHANGE YOUR FUEL FILTER EVERY 10,000 MILES...I HAVE HAD THIS SET UP IN MY TRUCK SINCE 2001...68,000 TROUBLE FREE MILES SINCE....GOOD LUCK
Expert:  JONATHAN replied 8 years ago.
P.S.BE CAREFUL AND DON'T MIX UP THE FUEL LINES...MATCH THEM TO THE EXACT CYLINDER PORTS IN THE INTAKE...AND DON'T ASK ME HOW I KNOW...LOL...CHASED A MISFIRE FOR HALF A DAY AFTER I INSTALLED IT...MIXED CYLS 1 AND 3 INJECTORS
Customer: replied 8 years ago.
Reply to JONATHAN's Post: Jonathan,
Good News. I replaced the CSFI unit with the new upgraded style and everything is working fine. Fuel pressure only went up to 58 psi from 52 but the startups are instant and with a very smooth idle. I did find out that the replacement CSFI unit is a dealer only item and not for release to AC Delco aftermarket. The part # XXXXX XXXXX I used my GM discount and it was much cheaper than trying to replace each of the old style poppets and regulator.
Thanks for all of your help.

P.S. I wasn't sure if I could post this reply after I chose accept so after I get your next reply I will accept.
Expert:  JONATHAN replied 8 years ago.
glad you're up and running....cool beans...
JONATHAN, JAGUAR/LAND ROVER SHOP FOREMAN
Category: Chevy
Satisfied Customers: 385
Experience: ASE MASTER TECHNICIAN L1 X1 CERIFICATIONS
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JONATHAN
JONATHAN
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ASE MASTER TECHNICIAN L1 X1 CERIFICATIONS